Those of you who have messed with splitters and air dams on your track cars, this question is for you.

I made up an air dam / splitter out of landscaping material. I have not added any downforce to the back of the car yet. Well, last weekend at Roebling, the car was really, REALLY loose. Just wondering if it's possible that the air dam is causing this?

 

no I just think its your busted *** car Karl

<---wishes his problem was this...bec that means I would have a race car

EDIT: in all honesty what I remember of physics (a lil) change the air current across a surface could greatly effect the way in which an object moves through the air so, I am guessing it may have an effect, what the degree is I have no clue, where is Scott when you need him...


[Modified by AcuraRacer112, 10:25 AM 9/27/2002]

 

Karl, as you know, I do not have any type of rear downforce device on my car, simply because I don't feel I need it.. I do notice, at faster speeds, that the RR gear splitter really does make the car want to oversteer a lot, but that is something that I don't mind at all... Now, was the car oversteering everywhere? Slow corners and Fast corners?

I really think its a hoosier tire issue, my car went from an understeering pig, to an Oversteering rocket, just by swapping hoosiers front to rear..

 

I don't mind a bit of oversteer, but this was excessive. Basically I'd turn in, and the tail would IMMEDIATELY swing out. I'd complete the corner with no steering input dialed in at all...often it was countersteer. This in long, 90-100mph sweepers. It was somewhat unsettling.

I was on Toyos last weekend. I know that's part of the problem, but the car was just wicked loose pretty much the whole weekend.

As to corner speeds, it's hard to say. Most of Roebling is high speed corners. The car was loose in the slow stuff too, but not quite as bad...? Hard to say.

I'd rather it not be quite this wild at VIR in a few weeks. Driving solo with a really loose car is one thing. But if I were wheel to wheel with the car like it was at Roebling, any time I checked up would have been an instant spin. It was that bad.

So then, assuming it's an aero thing...anyone got a recommendation on where to get a mad skillz wing that actually does something?

 

It would require more testing to be sure, but my relatively uneducated answer (based on the experiences with the airdam on my car) is yes. Especially as speeds increase. If in fact your new front areo is making the rear loose, pat yourself on the back for making effective splitter.

John -- who knows just enough about areo to get into trouble.

 

I hear APR makes tom tizzite wings yo! That'd balance it right out.

 

Something cheap and easy? *through gritted teeth* A Type R wing.

 

 

<-- tentatively pats self on back

I'll post pictures of the garden splitter this afternoon. It does have a little lip at the bottom - not *quite* a splitter, but damn close to it.

Not real sure what to do about the mad downforce now. I'm capable of driving the car the way it is. It just strikes me that there's approximately zero margin of error with the car handling like this. You need at least *some* margin of error - hell, I'm certainly no robot driver - so either I have to slow down a bit (not a good option), pull the splitter off (another not so good option), or...sigh...put some sort of mad skillz wing on the car.

Off to the classifieds I go, in search of a Type R wing. I'll paint it blue so it won't look *too* much like I'm copycatting Catch 22 and Warren

Keep the ideas coming all.

 

when did you install the splitter compared to when the problem started? I mean did you install it and the problem started? or have you been using it and it just appeared last race?


if you disrupt/remove enough air from under the car i could see a problem but thats ALOT of air for a "garden splitter"

 

It made its first appearance at Lowes, and then this Roebling event was its second appearance. I sucked so bad at Lowes I'm gonna throw that weekend away as a data collection weekend.

Dunno. I know part of the issue was going from Hoosiers to Toyos.

Here's a thought - I didn't run the 5mm rear spacers at Roebling. Perhaps the slightly smaller rear track made the car a bit more wild than usual?

Damn cars. It's always something. And if it's not, it's two or three things.

 

lol
im sure the tires had somthing to do with it, and so did the spacers but from what you said, the car is really loose too loose.

a type r wing would probably help. Or you could get an APC adjustable touring wing.
then you would have more mAd DoWnFoRcE SkILLz if it dosent rip off your trunk at 120mph.


[Modified by KAMiN, 12:51 PM 9/27/2002]

 

Is it possible to change and study one variable at a time during a track day? That would definitely help to isolate the cause(s).

Having never been to a track day or practice I don't know how much time you have...

 

Shultz, why break convention now? I'm sure you could make a return trip to Home Depot and buy the materials for one pimpy *** wing for pocket change. You have proven you are resourceful enough when you did the front splitter.
What would some brackets and plywood run you after all?
--Chris, who is desparately trying to find some pix of plywood super wings to show Karl the way.

 

Here you go...

 

Tough to say. I know you don’t have the luxury of another event before vir, but if yes I would run the car at least one more time at another track and see how it is. Because of T3 and T9 roebling is also the track where our car feels the most loose as well, probably as much as at road atlanta, which is another high speed track. Fast turns just do that to a car. It’s your call, but (in theory) the car will be fastest when you have 0 margin of error. It’s a compromise you have to make, but in T3 and T9 at roebling if you can take those turns with little or no steering input (after the initial turn in) you are flying. You can feel when the car is “right” and flying when you have to give little or no steering input to make a high speed turn, or some counter steering inputs if you don’t take it right one time or another. With the same setup on the car I spun out in T4 after a long slide in T3, but I didn’t change anything on the car since it is normal for it to turn this “well”. The car is able to take that turn at normal hot lap speed without basically any steering input in “good” conditions, but trying to take it at the same speed on very old tires in cooler temps for a few laps in a row, it finally came around big time once and I couldn’t get it straight before T4 to make that turn. But with good tires on the same setup the car takes it just right as it floats through any high speed turn. The downside is as you say that if you even have to breath off the gas even down to just 50% the car will come around. If you need to do that in something close to a “0 margin for error” car, then you’ll find yourself reacting to catch it before the car even starts sliding because you’re expecting it, so the chance that you will actually drive through it is still pretty good. All the fast racecars out there are (have to be) setup like this: as close to 0 margin of error as you can get it. But it’s still up to us how much of a compromise you want to have. I don’t know how your car drives, so it’s up to you to judge whether this is a problem and if so, how much of a problem this really is and then make your compromise for having a comfortable margin of error accordingly. Good luck!

 

Karl -

As someone else who dealt with wild oversteer this past weekend at Roebling -- it's the track, not the car. The long corners require a well planted car, and the pavement transitions are the enemy. Oversteer in transitions is acceptable, since the wheel is being opened anyways. My wife's car, which is an understeering pig, felt the best it ever has at Roebling.

Think about those pavement transitions -- front tires are on black (grippy?) stuff, back tires are on grey (slick?) stuff.

I made no changes at all to my car. It is neutral at VIR and an oversteering handful at RR. Result: Must have a tool for changing car balance at RR. Good tools = adjustable swaybar, adjustable aero.

If I were you, I would leave the car alone for VIR. Leaving the car alone will be the BEST way to determine if it is car, track, or driver. Maybe, just maybe, you can bring along a tool that can be changed if it is necessary after the first practice session.

I bet it will be fine -- most turns are transitional and the pavement is much more uniform. The only 2 turns at VIR that can cause problems like at RR are T1 and hogpen. There is a slick spot developing right at the apex in T1 -- I bet you will have Roebling flashbacks when you drive over that

 

.....I hate to say it, but maybe a mugen wing?

 

Dunno if this would help, but I'd let you borrow my ITR wing for awhile if you want to test it out. What the hell, my roof is on Scotts car.

 

Hey Karl,

My car was the same way at RR last weekend...and I have a BIG ole R wing and it still seemed WAY to rear happy for me....I tried all the usual suspects. Vittaco said it was probably just the track surface and I would need to adjust...so I did by slowing down

cheers

 

Why not cut/drill a few holes in the splitter Mugen/Wings West style to let some air through? Start out small, and you could slowly increase the size of the holes as needed.

Even better would be if you could make it so you had several different sized holes that you could take out and replace as needed. Tuneable front aero anyone?

 

I know that my little homemade front air dam made a huge difference in front grip in high speed corners. I also know that it slowed me down on straights (increased flat frontal area).

It didn't really make me loose though, it just helped stabilize the car.

Now I'm stepping up to the pimpy RRG piece thanks to my Lowes contigency .
We'll see how that goes.

As far as looseness in the ubertegra, I don't know. That car has always been a mystery to me because Karl's set-up is not at all aggressive yet the car has always tended to oversteer. Maybe something binding?
Maybe the crappy surface at Roebling + Binding suspension + the garden splitter = an evil loose integra???

 

Karl.

Air-dam and splitters that are effective will cause a loose feeling or rotation in rear with FWD cars. Very normal and congrats on getting the "Depot Spoiler" to cause this! Are you trying to put me out of business?

Scott is going to see this at VIR in practice. But, we will be able to adjust to the extra rotation until he feels comfortable.

Here the steps I take in order to help reduce or control oversteer........ IMHO.

1. drop rear pressures -2lb
( this works great on my car.... normally the only adjustment required)

2. soften the rear shocks
( I had to do this plus #1 at Lowes. Big overstreer in turn 2 prior )

3. soften the rear bar

4. last resort soften rear springs.

I like Corey like a loose car and normally 1 and or 2 on the list fix my oversteer until it's back to where I like it.

- Going back to work on Scotts new pimpy piece.

- Good Luck.

John
RoadRaceGear.com

 

I've run my car many times with and without my deluxe Home Depot cove base molding air dam. I did not notice any changes in the handling.

 

Dunno if this would help, but I'd let you borrow my ITR wing for awhile if you want to test it out. What the hell, my roof is on Scotts car.